It was shown in Section 6.3 that mode I fatigue crack growth occurs in notched specimens of polymers when subjected to fully compressive farfield cyclic loads.
(a) What are the mechanisms responsible for this effect?
(b) Discuss the possible effects of compressive stress amplitude and load ratio on the characteristics of crack initiation and growth from notches in polymers subjected to fully compressive cyclic loads.
(c) Can a fatigue crack be induced along the plane of a notch in a unidirectionally reinforced graphite-epoxy composite subjected to uniaxial cyclic compression, with the axis of the graphite fiber parallel to the compression axis and with the plane of the notch perpendicular to the compression axis?